Multilevel predictors of adolescent physical activity: a longitudinal analysis

Hearst, Patnode, Sirard, Farbakhsh Kian, Lytle

Description

To examine how factors from a social ecologic model predict physical activity (PA) among adolescents using a longitudinal analysis. Methods Participants in this longitudinal study were adolescents (ages 10-16 at baseline) and one parent enrolled in the Transdisciplinary Research on Energetics and Cancer-Identifying Determinants of Eating and Activity (TREC-IDEA) and the Etiology of Childhood Obesity (ECHO). Both studies were designed to assess a socio-ecologic model of adolescent obesity risk. PA was collected using ActiGraph activity monitors at two time points 24 months apart. Other measures included objective height and weight, adolescent and parent questionnaires on multilevel psychological, behavioral and social determinants of PA, and a home PA equipment inventory. Analysis was conducted using SAS, including descriptive characteristics, bivariate and stepped multivariate mixed models, using baseline adjustment. Models were stratified by gender. Results There were 578 adolescents with complete data. Results suggest few statistically significant longitudinal associations with physical activity measured as minutes of MVPA or total counts from accelerometers. For boys, greater self-efficacy (B = 0.75, p = 0.01) and baseline MVPA (B = 0.55, p < 0.01) remained significantly associated with MVPA at follow-up. A similar pattern was observed for total counts. For girls, baseline MVPA (B = 0.58, p = 0.01) and barriers (B = -0.32, p = 0.05) significantly predicted MVPA at follow-up in the full model. The full multilevel model explained 30% of the variance in PA among boys and 24% among girls. Conclusions PA change in adolescents is a complex issue that is not easily understood. Our findings suggest early PA habits are the most important predictor of PA levels in adolescence. Intervention may be necessary prior to middle school to maintain PA through adolescence.

Sujets

• Adolescence
• MultiLevel Recording
• Longitudinal

Informations

• Publié par: biomed
• Publié le: 01 janvier 2012
• Nombre de lectures: 10
• Langue: English

Extrait

Hearstet al.International Journal of Behavioral Nutrition and Physical Activity2012,9:8 http://www.ijbnpa.org/content/9/1/8

R E S E A R C H

Open Access

Multilevel predictors of adolescent physical activity: a longitudinal analysis 1* 2 3 1 1 Mary O Hearst , Carrie D Patnode , John R Sirard , Kian Farbakhsh and Leslie A Lytle

Abstract Background:To examine how factors from a social ecologic model predict physical activity (PA) among adolescents using a longitudinal analysis. Methods:Participants in this longitudinal study were adolescents (ages 1016 at baseline) and one parent enrolled in the Transdisciplinary Research on Energetics and CancerIdentifying Determinants of Eating and Activity (TREC IDEA) and the Etiology of Childhood Obesity (ECHO). Both studies were designed to assess a socioecologic model of adolescent obesity risk. PA was collected using ActiGraph activity monitors at two time points 24 months apart. Other measures included objective height and weight, adolescent and parent questionnaires on multilevel psychological, behavioral and social determinants of PA, and a home PA equipment inventory. Analysis was conducted using SAS, including descriptive characteristics, bivariate and stepped multivariate mixed models, using baseline adjustment. Models were stratified by gender. Results:There were 578 adolescents with complete data. Results suggest few statistically significant longitudinal associations with physical activity measured as minutes of MVPA or total counts from accelerometers. For boys, greater selfefficacy (B = 0.75,p= 0.01) and baseline MVPA (B = 0.55,p< 0.01) remained significantly associated with MVPA at followup. A similar pattern was observed for total counts. For girls, baseline MVPA (B = 0.58,p= 0.01) and barriers (B = 0.32,p= 0.05) significantly predicted MVPA at followup in the full model. The full multilevel model explained 30% of the variance in PA among boys and 24% among girls. Conclusions:PA change in adolescents is a complex issue that is not easily understood. Our findings suggest early PA habits are the most important predictor of PA levels in adolescence. Intervention may be necessary prior to middle school to maintain PA through adolescence. Keywords:Adolescent, Multilevel, Predictors of physical activity, Longitudinal

Background The U.S. Department and of Health and Human Ser vices recommends that children and adolescents engage in 60 min or more of physical activity (PA) every day, with most of that time in moderate to vigorousinten sity [1]. Engagement in moderatetovigorous physical activity (MVPA) typically decreases as adolescents move through their teen years. Examining data from a large adolescent cohort, Laska et al. showed that MVPA among girls declined from 5.9 h/week during the transi tion from early adolescence to midadolescence with a

* Correspondence: [e-mail] 1 Division of Epidemiology and Community Health, University of Minnesota, 1300 South Second Street, Suite 300, Minneapolis, MN 55454, USA Full list of author information is available at the end of the article

further decline to 3.5 h/week by late adolescence [2]. A similar, but less pronounced decline was also seen in boys. It is known that PA is inversely associated with cardiovascular disease risk factors during adolescence and into adulthood; [35] therefore, identifying and sub sequently intervening upon factors that help predict and promote adolescent PA over time is crucial for long term health outcomes. There have been several review articles in the past decade describing the correlates of PA among adoles cents [3,68]. The reviewers generally conclude that the state of the science is limited due to the complexity of the issue, limited external validity, and the lack of mea surement precision. Even studies using the most com plex multilevel models only explain a low percentage

© 2012 Hearst et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.